Summary

An Ubuntu installation system will be created that runs within the Ubuntu live CD environment, and works by copying and customizing the live CD filesystem rather than installing packages.

Rationale

The Ubuntu live CD inspires many people to install Ubuntu. At the moment, those people who downloaded the live CD then have to download another one in order to complete the installation. We should streamline this process. A live CD installer would be faster than the traditional installer within its limited use case, and would allow us to remain competitive with other popular live CD systems.

Scope and Use Cases

A user boots the live CD, falls in love with Ubuntu, and wants to use it forever after. They should be able to select an obvious icon on the desktop and launch the installer. S/he can install it in the hard disk or in a USB key, including the BootLoader in the harddisk or USB key.

A user wishes to use the live CD with the intent of installing the system immediately. They should be able to select a CD boot option which immediately launches the installer.

A user wishes to install a system based on a customized live CD environment (either a saved overlay or a custom root filesystem).

Requirements

The implementation should re-use existing installer components for configuration to the greatest extent possible, in order to share bugfixes and improvements

All install-time questions should be asked at the very beginning of the process, and then the installer should proceed non-interactively

The installer should display a single, clear progress bar for the remainder of the process

The result should be as close as possible to that of a normal installation

Design

Implementation Plan

Proposed Implementation

There are six major components to implement (either from scratch or based on existing code):

Installer Refactoring

We will reuse some installer components in the live environment, either by extracting udebs into a temporary directory or by unpacking the udebs using dpkg, and then by running some parts of them directly. We may need to take into account minor differences between debconf and cdebconf. Unpacking udebs into the ramdisk will require installing their dependencies too.

We will factor out the portions of grub-installer and yaboot-installer which deal with configuring and installing the bootloader rather than user interaction, and call those. All the partman* packages will be merged into a single source package (pending conversation with upstream) and made to generate a single normal binary package as well as the 20 or so udebs.

Some of the logic for locale, keymap, and timezone selection may need to be factored out of localechooser, kbd-chooser, and base-config respectively, to avoid duplicating complex code with many special cases.

The detect-keys plugin may need to be factored out of cdebconf and kbd-chooser, depending on the outcome of LiveCDPrompts.

Other Issues

Since we only intend to offer GRUB as the bootloader on i386/amd64 systems, we may need to disable some partitioning choices that currently cause the installer to fall back to LILO. Currently, installations with /boot on either an XFS filesystem or an LVM logical volume do not work reliably with GRUB under all circumstances.

We need to honor debconf preseeding to facilitate the creation of customized live CDs. This may involve adjusting the way that casper silences certain installer questions.

Data Preservation and Migration

Packages Affected

base-config

casper

grub-installer

kbd-chooser

localechooser

partman*

yaboot-installer

User Interface Requirements

Should be simple

Should be able to use GNOME or KDE UI elements

Outstanding Issues

UDU BOF Agenda

How to refactor existing installer components to allow them to be used in the live environment

Custom components needed

Graphical partitioner

User interface

GNOMEish frontend (but allow for KDEish frontend as well)

Limitations

Can't be used for upgrades

Can't easily be used for server installations (especially not via serial console)

Specialized for the common case desktop installation

UDU Pre-Work

Check out knoppix-installer

(you should also check out the Installer of Kanotix, a breeding place of many things that are now in Knoppix, also the new knoppix-installer is derived from Kanotix -> http://kanotix.com/index.php?&newlang=eng